1. Field of the Invention
The present invention relates generally to microelectrode array devices and methods of detecting physiological signals within a body.
2. Related Art
The potential for implanting electronic devices into patients with direct interface to the neural system is vast. Systems which may enable paraplegics to regain control of their bladder or limbs, provide vision for the blind, or restore vocal cord function are all under development, and promising initial results have been obtained in some experiments.
A key component of some implantable systems is a needle array to enable interfacing of the electronics with a nerve or directly with neuron in brain tissue. For example, U.S. Pat. No. 5,215,088 to Norman et al. discloses a three-dimensional electrode device which can be used as a neural or cortical implant. The device of Norman, also known as the Utah Electrode Array (UEA), can be used to provide a neural interface to electronic equipment for sensing and/or stimulation of physiological signals and pathways and has been successfully used in a large number of patients. However, difficulties and challenges of this system are still present which limit its effectiveness and potential applications. Biological organisms, from the simple to the substantially complex, can include a wide range of different physiological signals and pathways for the signals to travel. The large number of different signals and pathways can cause biological organisms to be a relatively noisy electrical environment. Neural and nerve impulses tend to have a relatively low amplitude in comparison to surrounding competing signals from other physiological systems, e.g. muscles. Accurately sensing and/or activating these signals and pathways within this noisy environment can be challenging.